can I get the bus from beijing airport to guangzhou Saturday 21 sep at 10pm and how much in american dollars and what is the latest bus,how long is the trip.

Hi, it is more than 2,000km between BJ and Guangzhou, so bus might not be a good idea. It is suggested to take the direct plane to reach in around 3h. The air ticekt fare varies a lot from time to time. On Sep. 21, it should be a little more than CNY1,000 (163USD) for the economy class seat.

Or the high-speed train between is also a good choice. I suggest you stay in BJ for a night and take G-train to Guangzhou in the next morning. It takes around 8h and it costs CNY862 (140USD) for a second class seat and CNY1,380 (225USD) for a first class seat.